A growing number of fastball pitchers are throwing at speeds reached by only a handful of hurlers a decade ago. Why the velocity revolution hit warp speed, and what it means for baseball.

As Major League Baseball prepares to open its season Sunday, high-octane pitching is dominating the game as never before. One day it's the Cincinnati Reds' Aroldis Chapman, the"Cuban Missile," firing 103-mile-per-hour fastballs out of the bullpen. The next, starters like the Washington Nationals' Stephen Strasburg and the Tampa Bay Rays' David Price are clocking triple digits deep into games when they should be tiring.

Dylan Bundy, the Baltimore Orioles' 20-year-old, started lifting weights when he was 10, and he threw in the high-80s in middle school. He broke 90 as a freshman in high school, and had hit 100 before graduation. Getty Images

In the 2003 season, there was only one pitcher who threw at least 25 pitches 100 mph or faster (Billy Wagner). In 2012, there were seven, according to Baseball Info Solutions.

In 2003, there were only three pitchers who threw at least 700 pitches 95 mph or better. In 2012, there were 17. There were 20 pitchers a decade ago who threw at least 25% of their fastballs 96 mph or faster. Last year there were 62, including Carter Capps, the Seattle Mariners' 22-year-old right-hander, whose average fastball travels 98.3 mph, tying him with the Royals' Kelvin Herrera for the top spot in the game.

A motion analysis lab in New York City uses 2-D and 3-D video technology to research and improve the throwing motion of baseball pitchers. WSJ's Matthew Futterman visits the lab for answers about his short-lived pitching career.

At the same time, just a decade after performance-enhancing drugs helped power an unprecedented boom in offense, hitters are spiraling into ineptitude. Last season the game's batters struck out 36,426 times, an 18.3% increase over 2003.

"It's pretty simple," said Rick Peterson, director of pitching development for the Baltimore Orioles, who sees a direct link between strikeouts and the increase in velocity. "The harder you throw, the less time the batter has to swing and the harder it is to make contact. Everybody can square up a slow-pitch softball. A 95-mile per hour fastball is a little different."

Nearly 20% of all plate appearances last season resulted in a strikeout. In 1968, just 15.8% of plate appearances resulted in strikeouts. And that was the so-called "year of the pitcher," when the dominance of the likes of Bob Gibson and Denny McLain caused baseball to lower the mound and begin experimenting with a designated hitter.

Baseball's speed revolution is an outgrowth of a series of radical—and sometimes surprising— shifts in the way both children and adults approach the game at every level.

This isn't just about bigger, stronger athletes. In terms of the stress placed on a human body part, nothing in sports compares with what the shoulder undergoes when a top pitcher throws a fastball. The joint can rotate at roughly 7,000 degrees per second. Since a full rotation equals 360 degrees, the arm would complete nearly 20 full rotations in a single second if it were physically able.

"That's about as fast as a human joint can move, so pitchers probably won't ever throw much faster than they do now," said Glenn Fleisig, a biomedical engineer at the American Sports Medicine Institute in Alabama and one of the leading researchers in the science of pitching. "But now you're seeing more and more pitchers every year getting close to the ceiling, so the question becomes, why?"

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Aroldis Chapman, the 'Cuban Missile,' and reliever for the Cincinnati Reds was clocked at 105.1 mph in 2010.
Photo illustration by John Kuczala; Getty Images (pitchers)

Part of the flamethrowing trend is a function of simple economics. The best pitchers now command some of the game's highest salaries. Being merely average is worth $11.5 million a year (Bronson Arroyo, 12-10, 3.74 earned-run average). As a result, the game's biggest and best young athletes are gravitating toward the pitching mound.

On average, the game's pitchers have gained about a half-inch in height since 2000, according to Adrian Bejan, an engineering professor at Duke University, who studies sports evolution and wrote a recent study of body size in baseball.

That makes sense, Bejan reasons, because the pitching motion mimics the action of a trebuchet, the medieval weapon for throwing stones against heavy fortifications. Early designers of trebuchets figured out the key to flinging a stone faster was increasing the height of the body and the length of the arm and rope, which together function like the pitcher's body and arm. A longer rope just required more weight to propel it forward. Baseball scouts have essentially come to the same conclusion. Think Randy Johnson, who is 6-foot-10, or even Capps, who is 6-foot-5.

Then there's technology. Twenty years ago, the actual speed of a pitch was information usually reserved for scouts with clunky radar guns. Now, with more accurate laser technology, that information is on the scoreboard in every stadium and noted pitch by pitch on nearly every telecast. A decent gun can be had for less than $200 and is about the size of a hair dryer. There are iPhone apps, too: Little League dads track how hard their 9-year-olds throw. Today's flamethrowers are the first generation to be raised in a baseball culture obsessed with velocity.

It's easy to understand why. In a data-crazed era when franchises demand their scouts and executives back up every strategy and draft pick with numbers, velocity stands alone as the only statistical characteristic that doesn't depend on the quality of the opponent—as do hitting and other pitching stats. That makes it the logical place to begin any evaluation, said John Mozeliak, general manager of the St. Louis Cardinals.

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Carter Capps
Getty Images

"At a certain speed, you're able to get away with more mistakes," Mozeliak says.

Chris Holt, a former major-leaguer who now coaches prospects at Pro Bound USA, a Florida baseball academy, says young pitchers who can't hit 90 on the radar gun don't get a serious look. "Ninety-two is the new 88," he says. "The cutoff is 90, 91 minimum."

Well aware of this obsession with measurement and velocity, young pitchers and their coaches began about 15 years ago to approach the game with a singular goal: figuring out how to throw the ball as hard as they can.

"The main reason people are throwing hard is because they see the value of getting noticed throwing harder," said Ron Wolforth, whose Texas Baseball Ranch has become one of the top destinations for aspiring fireballers. Wolforth is one of the leaders of what is fast becoming a dominant school of pitching thought. He and his disciples, who are sprinkled throughout the baseball-talent hotbeds in the American South and West, stress a free and athletic-style throwing motion that harnesses the power of the entire body, but especially the legs and core muscles. It's based partly on what Dominican and Venezuelan pitchers have been practicing for years. ("You don't get off the 'island' throwing curveballs," the saying goes; Venezuelan Bruce Rondon, a Tigers prospect, throws 104.) The philosophy puts far less emphasis, especially at the beginning, on controlled mechanics and more on learning and practicing what Holt refers to as "throwing the heck out of the baseball."

Matthew Futterman explains how the increasing number of pitchers who regularly throw 100 mph is changing baseball. Photo: Getty Images.

Capps, the Seattle Mariners' rising star, is a prime example of this approach. He was a catcher until his freshman year at Mount Olive College in North Carolina. He had a decent arm but wasn't much of a hitter, and the team already had an All-American catcher. Head coach Carl Lancaster suggested he try to pitch.

Capps hit the weight room to add muscle to his 170-pound frame. He started long-tossing, that is, playing catch at more than 250 feet, and he began to work on his mechanics so he could use his long legs to extend his stride and leverage his height. By the beginning of his sophomore year he was registering 93 to 95 miles per hour on the radar gun. The following summer, he hit 97 during the All-Star Game of the Coastal Plains League, a summer-league for college players. "After that he never touched the rubber at our place without a crowd of scouts watching," Lancaster said.

"The harder you throw, the cleaner it feels," Capps said during a recent interview from spring training. "It's actually less stress on the arm, because when I'm throwing my hardest, my legs are doing all the work and my upper body is coming right through."

Although pitchers last year spent 29.1% more days on the disabled list than they did in 2003, most orthopedists blame that on overwork, not rising velocity.

At laboratories at the American Sports Medicine Institute in Alabama and the Hospital for Special Surgery in New York, orthopedists and biomechanists place dozens of sensors on pitchers and have them throw in front of a series of infrared cameras that measure their motions and turn the windup into a three-dimensional computer graphic. Then they analyze the data to try to see if all the parts of the body are synchronizing, with each of the six separate actions of the motion flowing methodically from one into the next.

"It's a kinetic chain," Fleisig said. "You rotate the hips at the right time, and then the torso and then the shoulders and then the arm and elbow."

It follows that the stronger the links of the chain are, the faster the pitch, which has led to a sea change in the way pitchers train. Gone are the days when strength and conditioning meant visiting the weight room a few days a week with an assistant football coach.

"It's about being strong in the core, the glutes [rear end], the hips and the obliques, and that's what everyone is working on," said Stephen Fealy, an orthopedic surgeon at the Hospital for Special Surgery and a pitching consultant to the Major League Baseball Players Association.

Consider Dylan Bundy, the Baltimore Orioles' 20-year-old, white-hot prospect. Bundy started lifting weights when he was 10, and he threw in the high 80s in middle school. He broke 90 as a freshman in high school and had hit 100 before graduation. To build up his legs, core, arm and hands, he and his brother and father would toss tires, dig holes and refill them, push wheelbarrows full of dirt, cut down trees with an ax and split wood. He also long-tossed up to 350 feet, and still does, all in pursuit of getting stronger and maximizing velocity.

"The velocity allows you to get away with some mess-ups," Bundy says. "Who knows? I may still have a few miles per hour left in the tank."

That will likely mean more bad news for opposing hitters. To be sure, velocity isn't the only cause for their mounting futility. A recent statistical analysis of velocity and effectiveness by Frangraphs.com suggested that increased velocity may explain as little as 25% of overall pitching success. Pitchers have become better at mixing speeds and locations, too.

Sabermetrics, the data-centric approach that prizes doubles and home runs over singles and stolen bases, hasn't done hitters any favors either. It encourages them to keep swinging for the fences, even with two strikes. And just as this generation of pitchers grew up hooked on velocity, hitters in their prime today came of age in the homer-happy steroid era. The game's prevailing economic model continues to deliver that message. Prince Fielder makes nearly $24 million a year for averaging 36 home runs and 33 doubles, even though he also strikes out 121 times over 162 games.

The problem for baseball over the long term is that the strikeout is the one offensive event that hardly ever sets into motion an unpredictable result. The batter generally mopes back to the dugout. Some fans find it boring, and some purists find it lame.

"Guys don't seem to care about striking out anymore, but when you strike out, you're not putting the ball in play, and when you don't do that, nothing can happen," said Keith Hernandez, the former batting champion who is now a television analyst for the Mets. Even the National League is no longer home to a style of baseball that values speed and contact hitting over hacking and hoping for the long ball, he says.

For now though, Major League Baseball isn't inclined to tinker with the balance and cut down on strikeouts. Tony La Russa, the former manager who has served as a consultant to Commissioner Bud Selig, said the sport isn't necessarily about what's most exciting.

"It's about how you can win games," La Russa said. "That should mean with two strikes you have to fight to put the ball in play. But," he admits, "that's easier said than done because of these pitchers."

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